The approaches described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section.
Successfully harvesting corn grain depends on many managerial factors including hybrid selection, soil fertilization, irrigation, and pest control which each contribute to the growth rate of corn plants. These factors must be accounted for when determining the optimal time to harvest the corn grain. Harvesting times relative to the corn maturity is especially important because water content of corn grain, when harvested, affects the sales price of the bushel of corn harvested. Grain moisture is used to determine a sales price per bushel of a particular grade of corn. Grain moisture refers to and is measured as the ratio of water mass to wet kernel mass. The grain moisture level is important to buyers because the level of moisture in grain can affect the amount of degradation of grain during storage and shipment. If a grower harvested corn that has higher than desired grain moisture, then buyers may demand a discount for the harvested corn. The loss or cost may be significant.
As the corn plant grows, it progresses through multiple growth stages of development. These stages are identified by physical traits of the corn plant. Stages include multiple vegetative stages that track growth of the corn plant leaves and reproductive stages that track development of the corn kernels. During the vegetative and reproductive stages the corn plant transfers water and nutrients collected by the corn plant to the kernels. During maturation the amount of kernel moisture begins to slowly decrease. When the kernel reaches physiological maturity, referred to as R6 stage, there is a passive exchange of moisture between the kernel and outside air. The R6 stage is also referred to as “black layer” because physiological maturity occurs when a black layer forms at the base of the kernels. The black layer is a hard starch layer that turns black or brown and cuts off the water and dry matter transfer to the kernel. Once the R6 stage is reached the decrease in kernel moisture is primarily due to the rate of water loss from the kernel itself to outside air. This rate is referred to as grain dry down.
Reaching the R6 layer and the subsequent grain dry down are influenced by many factors, including the ambient air temperature and humidity and absorption of water and nutrients by the corn plant during the vegetative and reproductive phases. Watering strategies and the amount of nutrients in the soil may affect the overall starting grain moisture at R6. Therefore understanding and tracking the multiple vegetative and reproductive stages during corn plant growth are desirable for planning when to apply nutrients, such as nitrogen to the soil, and when to deliver water based on the corn growth stage.
Historically harvest times, based upon the predicted R6 date, may be modeled using the weather, hybrid seed type, and historical data. Since R6 begins when the physical black layer at the base of the kernel starts, visual observation is not possible unless the corn is dissected; therefore growers estimate the beginning of the R6 stage using models that approximate R6 based on data provided by hybrid seed producers and observed temperature data from previous harvests of the hybrid seeds. However, approximating the start of R6 based solely upon historical data does not take into account specific variances of the corn plant based upon direct physical observations of the planted corn. Individual fluctuations between grain moisture content at R6 for specific hybrid seed varieties may lead to errors when predicting harvest times based upon a target grain moisture content at harvest.